Compositions of optically pure (+) norcisapride

ABSTRACT

Compositons employing and methods utilizing the optically pure (+) isomer of norcisapride are disclosed. This compound has surprisingly been found to be a potent drug for the treatment of disorders of the central nervous system. The compound, (+) norcisapride, has also been found to be a potent antiemetic agent. Finally the (+) isomer of norcisapride also avoids certain adverse side effects and certain adverse drug interactions.

This application is a continuation of application Ser. No. 09/123,892,filed Jul. 28, 1998, now U.S. Pat. No. 6,147,093, which is acontinuation-in-part of application Ser. No. 08/905,941, filed Aug. 5,1997, now U.S. Pat. No. 5,877,188, which is a divisional of applicationSer. No. 08/684,753, filed Jul. 19, 1996, now U.S. Pat. No. 5,739,151.

1. FIELD OF THE INVENTION

The present invention relates to methods and compositions for treatingcentral nervous system (“CNS”) disorders, emesis, and disordersassociated with gastrointestinal motility dysfunction. In anotheraspect, this invention relates to metabolites of cisapride and opticalisomers of such metabolites.

2. BACKGROUND OF THE INVENTION 2.1. Steric Relationship and Drug Action

Many organic compounds exist in optically active forms, i.e., they havethe ability to rotate the plane of plane- polarized light. In describingan optically active compound, the prefixes D and L or R and S are usedto denote the absolute configuration of the molecule about its chiralcenter(s). The prefixes d and l or (+) and (−) are employed to designatethe sign of rotation of plane-polarized light by the compound, with (−)or l meaning that the compound is levorotatory. A prefix of (+) or dindicates that the compound is dextrorotatory. For a given chemicalstructure, these compounds, called stereoisomers, are identical exceptthat they are mirror images of one another. A specific stereoisomer mayalso be referred to as an enantiomer, and a mixture of such isomers isoften called an enantiomeric or racemic mixture.

Stereochemical purity is of importance in the field of pharmaceuticals,where many of the most prescribed drugs exhibit chirality. A case inpoint is provided by the beta-adrenergic blocking agent, propranolol,where the S-enantiomer is known to be 100 times more potent than theR-enantiomer. However, potency is not the only concern in the field ofpharmaceuticals.

2.2. Pharmacologic Action

U.S. Pat. Nos. 4,962,115, 5,057,525 and 5,137,896 (collectively “VanDaele”) disclose N-(3-hydroxy-4-piperidenyl)benzamides includingcisapride. These compounds are said to stimulate the motility of thegastrointestinal system. Van Daele states that the cis and transdiastereomeric racemates of these compounds may be obtained separatelyby conventional methods, and that the cis and trans diastereomericracemates may be further resolved into their optical isomers.

Cisapride is one of a class of compounds known as benzamide derivatives.(See: Schapira et al., Acta Gastroenterolog. Belg. LIII: 446-457, 1990).As a class, these benzamide derivatives have several prominentpharmacological actions. The prominent pharmacological activities of thebenzamide derivatives are due to their effects on the neuronal systemswhich are modulated by the neurotransmitter serotonin. The role ofserotonin, and thus the pharmacology of the benzamide derivatives, hasbeen broadly implicated in a variety of conditions for many years (SeePhillis, J. W., “The Pharmacology of Synapses”, Pergamon Press,Monograph 43, 1970; Frazer, A. et al., Annual Rev. of Pharmacology andTherapeutics 30: 307-348, 1990). Thus, research has focused on locatingthe production and storage sites of serotonin as well as the location ofserotonin receptors in the human body in order to determine theconnection between these sites and various disease states or conditions.

In this regard, it was discovered that a major site of production andstorage of serotonin is the enterochromaffin cell of thegastrointestinal mucosa. It was also discovered that serotonin has apowerful stimulating action on intestinal motility by stimulatingintestinal smooth muscle, speeding intestinal transit, and decreasingabsorption time, as in diarrhea. This stimulating action is alsoassociated with nausea and vomiting.

Because of their modulation of the serotonin neuronal system in thegastrointestinal tract, many of the benzamide derivatives are ofteneffective antiemetic agents and are commonly used to control vomitingduring cancer chemotherapy or radiotherapy, especially when highlyemetogenic compounds such as cisplatin are used (See: Costall et al.,Neuropharmacology 26: 1321-1326, 1987). This action is almost certainlythe result of the ability of the compounds to block the actions ofserotonin (5HT) at specific sites of action, such as the 5HT3-receptor,which was classically designated in the scientific literature as theserotonin M-receptor (See: Clarke et al., Trends in PharmacologicalSciences 10: 385-386, 1989). Chemo- and radio-therapy may induce nauseaand vomiting by the release of serotonin from damaged enterochromaffincells in the gastrointestinal tract. Release of the neurotransmitterserotonin stimulates both afferent vagal nerve fibers (thus initiatingthe vomiting reflex) and serotonin receptors in the chemoreceptortrigger zone of the area postrema region of the brain. The anatomicalsite for this action of the benzamide derivatives, and whether suchaction is central (CNS), peripheral, or a combination thereof, remainsunresolved (See: Barnes et al., J. Pharm. Pharmacol. 40: 586-588, 1988).

A second prominent action of the benzamide derivatives is in augmentinggastrointestinal smooth muscle activity from the esophagus to theproximal small bowel, thus accelerating esophageal and small intestinaltransit as well as facilitating gastric emptying and increasing loweresophageal sphincter tone (See: Decktor et al., Eur. J. Pharmacol. 147:313-316, 1988). Although the benzamide derivatives are not cholinergicreceptor agonists per se, the aforementioned smooth muscle effects maybe blocked by muscarinic receptor blocking agents such as atropine orinhibitors of neuronal transmissions such as the tetrodotoxin type whichblock sodium channels (See: Fernandez and Massingham, Life Sci. 36:1-14, 1985). Similar blocking activity has been reported for thecontractile effects of serotonin in the small intestine (See: Craig andClarke, Brit. J. Pharmacol. 96: 247P, 1989). It is believed that theprimary smooth muscle effects of the benzamide derivatives are theresult of an agonist action upon a class of serotonin receptors referredto as 5HT4 receptors which are located on interneurons in the myentericplexus of the gut wall (See Clarke et al., Trends in PharmacologicalSciences 10: 385-386, 1989 and Dumuis et al., N. S. Arch. Pharmacol.340: 403-410, 1989). Activation of these receptors subsequently enhancesthe release of acetylcholine from parasympathetic nerve terminalslocated near surrounding smooth muscle fibers. It is the combination ofacetylcholine with its receptors on smooth muscle membranes which is theactual trigger for muscle contraction.

Cisapride possesses similar properties to metoclopramide except that itlacks dopamine receptor blocking activity (See: Reyntjens et al., Curr.Therap. Res. 36: 1045-1046, 1984) and enhances motility in the colon aswell as in the upper portions of the alimentary tract (See: Milo, Curr.Therap. Res. 36: 1053-1062, 1984). The colonic effects, however, may notbe completely blocked by atropine and may represent, at least in part, adirect action of the drug (See: Schuurkes et al., J. Pharmacol Exp.Ther. 234: 775-783, 1985). Using cultured mouse embryo colliculi neuronsand cAMP generation as an endpoint for designating 5HT4 activity, theEC50 concentration of racemic cisapride was 7×10⁻⁸ M (See: Dumuis etal., N. S. Arch. Pharmacol. 340: 403-410, 1989). Drugs of this class donot affect gastric acid secretion and have variable effects upon colonicmotility (See: Reyntjens et al., Curr. Therap. Res. 36: 1045-1046, 1984and Milo, Curr. Therap. Res. 36: 1053-1062, 1984).

Racemic cisapride is used primarily to treat gastro-esophageal refluxdisease, which is characterized as the backward flow of the stomachcontents into the esophagus. Cisapride is available only as a 1:1racemic mixture of optical isomers, called enantiomers, i.e., a mixtureof cis(−) and cis(+) cisapride known as “Prepulsid™.”

The observation that cisapride enters the central nervous system andbinds to 5HT4 receptors indicates that cisapride may havecentrally-mediated effects. As was shown by Dumuis et al., N.S. Arch.Pharmacol. 340: 403-410, 1989, cisapride is a potent ligand at 5HT4receptors, and these receptors are located in several areas of thecentral nervous system. Modulation of serotonergic systems may have avariety of behavioral effects.

Because of its activity as a prokinetic agent, cisapride may also beuseful to treat dyspepsia, gastroparesis, constipation, postoperativeileus, and intestinal pseudo-obstruction.

Dyspepsia is a condition characterized by an impairment of the power orfunction of digestion that can arise as a symptom of a primarygastrointestinal dysfunction or as a complication due to other disorderssuch as appendicitis, gallbladder disturbances, or malnutrition.Gastroparesis is a paralysis of the stomach brought about by a motorabnormality in the stomach or as a complication of diseases such asdiabetes, progressive systemic sclerosis, anorexia nervosa or myotonicdystrophy. Constipation is a condition characterized by infrequent ordifficult evacuation of feces resulting from conditions such as lack ofintestinal muscle tone or intestinal spasticity. Post-operative ileus isan obstruction in the intestine due to a disruption in muscle tonefollowing surgery. Intestinal pseudo-obstruction is a conditioncharacterized by constipation, colicky pain, and vomiting, but withoutevidence of physical obstruction.

The co-administration of racemic cisapride with another therapeuticagent causes inhibitory problems with the metabolism of cisapride by theliver. For example, ketoconazole has a pronounced effect on cisapridekinetics resulting from the inhibition of the metabolic elimination ofcisapride and leading to an 8-fold increase in steady-state plasmalevels. (See: Lavrijsen, K., et al. “The Role of CYP3A4 in the In-vitroMetabolism of Cisapride in the Human Liver Microsomes an In-vitro andIn-vivo Interactions of Cisapride with Co-administered Drugs,”Department of Pharmacokinetics and Drug Metabolism, Janssen ResearchFoundation, Beerse, Belgium). Interaction of racemic cisapride andanother therapeutic agent can also potentiate cardiovascular sideeffects, such as cardiotoxicity. This potentiation occurs when otherdrugs present in the patient's system interfere with the metabolism ofracemic cisapride, thereby building up racemic cisapride in the body.These interactions are a significant drawback to the use of racemiccisapride; in particular, because racemic cisapride is often usedbefore, during or immediately after another therapeutic agent.

In addition, administration of cisapride to a human has been found tocause adverse effects including, tachycardia, central nervous system(“CNS”) effects, increased systolic pressure, interactions with otherdrugs, diarrhea, abdominal cramping, and cardiac depression. Further, ithas been reported that intravenous administration of racemic cisapridedemonstrates the occurrence of additional adverse (side) effects notexperienced after oral administration of racemic cisapride. (See:Stacher et al. Digestive Diseases and Sciences 32(11):1223-1230 (1987)).

Cisapride is almost completely absorbed after oral administration tohumans, but bioavailability of the parent compound is only 40-50%, dueto rapid first pass metabolism in the liver (See: Van Peer et al., inProgress in the Treatment of Gastrointestinal Motility Disorders: TheRole of Cisapride. Proceedings of a Symposium in Frankfurt. November1986. Johnson A. G. and Lux, G. eds. Excerpta Medica, Amsterdam, pp.23-29 (1988)). More than 90% of a dose of cisapride is metabolizedmainly by oxidative N-dealkylation at the piperidine nitrogen or byaromatic hydroxylation occurring on either the 4-fluorophenoxy orbenzamide rings. It is the piperidinylbenzamide moiety of themetabolized cisapride which is identified as norcisapride. (See:Meuldermans, W. et al., Drug Metab. Dispos. 16(3): 410-419, 1988 andMeuldermans, W. et al., Drug Metab. Dispos. 16(3): 403-409, 1988).Metabolism of cisapride to norcisapride is believed to occur as follows:

Norcisapride is the main urinary metabolite comprising 50-80% of thedrug found in the urine of humans 72 hours after dosing. (See:Meuldermans, W. et al., Drug Metab. Dispos. 16(3): 410-419, 1988). Shortduration of action, as seen with cisapride, can often be associated witherratic pharmacological effects following oral administration ofcompounds.

Thus, it would be particularly desirable to find a compound with theadvantages of cisapride which would not have the aforementioneddisadvantages.

3. SUMMARY OF THE INVENTION

The present invention relates to novel compositions of matter containingoptically pure (+) norcisapride which are useful in treating CNSdisorders. It has further been discovered that such treatment may beaccomplished while substantially reducing adverse effects associatedwith the administration of racemic cisapride, including but not limitedto diarrhea, abdominal cramping, cardiac depression and elevations ofblood pressure and heart rate.

It has also been discovered that optically pure (+) norcisapride is aneffective antiemetic agent, useful as an adjunctive therapy in cancertreatment to alleviate nausea and vomiting induced by chemo- orradio-therapeutics. In addition, optically pure (+) norcisapride may beused to treat emesis while substantially reducing the above-describedadverse effects associated with the administration of racemic cisapride.

It has also been discovered that these novel compositions of mattercontaining optically pure (+) norcisapride are useful in treatinggastro-esophageal reflux disease and such other conditions as may berelated to the activity of (+) norcisapride as a prokinetic agent, e.g.,dyspepsia, gastroparesis, constipation, post-operative ileus, andintestinal pseudo-obstruction. In addition, optically pure (+)norcisapride may be used to treat such conditions while substantiallyreducing the above-described adverse effects associated with theadministration of racemic cisapride.

Thus, the present invention includes methods for treating theabove-described conditions in a human by administering optically pure(+) norcisapride to said human. The present invention also includesmethods and compositions which demonstrate an improved bioavailabilityover racemic cisapride irrespective of the mode of administration.Furthermore, the present invention also includes methods andcompositions for treating human disease states by having the unexpectedbenefit of being able to administer both optically pure (+) norcisaprideand another therapeutic agent without the inhibitory effects commonlyassociated with the co-administration of cisapride and anothertherapeutic agent, e.g., adverse drug interaction.

The use of optically pure (+) norcisapride has been found to be superiorto racemic cisapride or racemic norcisapride in treating theabove-mentioned disease states.

4. DETAILED DESCRIPTION OF THE INVENTION

This invention relates to novel compositions of matter containingoptically pure (+) norcisapride. These compositions possess activity intreating emesis. Additionally, these novel compositions of mattercontaining optically pure (+) norcisapride may be used to treat otherconditions that may be related to the activity of (+) norcisapride as aprokinetic agent, including but not limited to dyspepsia, gastroparesis,constipation, and intestinal pseudo-obstruction. Moreover, opticallypure (+) norcisapride may be used to treat these conditions whilesubstantially reducing or avoiding adverse effects associated with theadministration of racemic cisapride.

Further, the present invention encompasses the use of (+) norcisapride,substantially free of its (−) isomer, to treat central nervous system(“CNS”) disorders including, e.g., but not limited to depression, mania,bipolar affective disorder, anxiety, and panic disorder. Also disclosedare methods for treating the above-described conditions in a human whilesubstantially reducing adverse effects that are associated withcisapride, including but not limited to diarrhea, abdominal cramping,cardiac depression, and elevations of blood pressure and heart rate, byadministering the (+) isomer of norcisapride, substantially free of its(−) isomer, to a human in need of such treatment. In addition, accordingto the present invention, optically pure (+) norcisapride may be used totreat CNS disorders while substantially avoiding or reducing the adverseeffects associated with drugs used to treat CNS disorders, e.g., such asbenzodiazepines. Further disclosed are methods of treating variousdisease states in humans by co-administering optically pure (+)norcisapride and another therapeutic agent, while unexpectedly avoidingthe adverse effects associated with administering cisapride and atherapeutic agent.

The active compound of these compositions and methods is an opticallypure isomer of a metabolic derivative of cisapride, which metabolicderivative is described in Meuldermans, W. et al., Drug Metab. Dispos.16(3): 410-419, 1988 and Meuldermans, W. et al., Drug Metab. Dispos.16(3): 403-409, 1988.

Chemically, the active compound, of the presently disclosed compositionsand methods, is the (+) isomer of the metabolic derivative ofcis-4-amino-5-chloro-N-[1-[3-(4-fluorophenoxy)propyl]-3-methoxy-4-piperidinyl]-2-methoxybenzamide(hereinafter referred to as “cisapride”), known as4-amino-5-chloro-N-(3-methoxy-4-piperidinyl)-2 methoxybenzamidehereinafter referred to as “(+) norcisapride.” The term “(+) isomer ofnorcisapride” and particularly the term “(+) norcisapride” encompassoptically pure and substantially optically pure (+) norcisapride.Similarly, as used herein, the terms “racemic cisapride”, “racemicnorcisapride” or “racemic mixture of cisapride” or “racemic mixture ofnorcisapride” refer to the cis diastereomeric racemates.

The present invention encompasses a method of treating CNS disorders ina human, and methods of treating CNS disorders in a human whilesubstantially reducing the concomitant liability of adverse effectsassociated with the administration of racemic cisapride, which comprisesadministering to a human in need of such treatment, a therapeuticallyeffective amount of (+) norcisapride, or a pharmaceutically acceptablesalt thereof, substantially free of its (−) stereoisomer. In particular,(+) norcisapride can be used to treat a variety of CNS disordersincluding but not limited to (1) cognitive disorders such as Alzheimer'sdisease, senile dementia; (2) behavioral disorders such asschizophrenia, mania, obsessive-compulsive disorder and psychoactivesubstance use disorders; (3) mood disorders such as depression, bipolaraffective disorder, anxiety and panic disorder; (4) disorders of controlof autonomic function such as hypertension and sleep disorders; and (5)neuropsychiatric disorders, such as Gilles de la Tourette's syndrome,and Huntington's disease. These and other related disorders are wellknown in the art; therefore, it will be apparent to the skilled artisanbased on this disclosure what other related disorders may be treated by(+) norcisapride in accordance with this invention.

In a preferred embodiment, (+) norcisapride is used to treat mooddisorders, such as depression, bipolar affective disorder, anxiety andpanic disorder, and behavioral disorders, such as schizophrenia, mania,and more preferably, mood disorders.

The present invention also encompasses a pharmaceutical composition forthe treatment of a human suffering from a CNS disorder, which comprisesa therapeutically effective amount of (+) norcisapride, or apharmaceutically acceptable salt thereof, substantially free of its (−)stereoisomer.

The present invention further encompasses a method of eliciting anantiemetic effect in a human which comprises administering to a human inneed of such antiemetic therapy, a therapeutically effective amount of(+) norcisapride, or a pharmaceutically acceptable salt thereof,substantially free of its (−) stereoisomer.

In addition, the present invention encompasses an antiemetic compositionfor the treatment of a human in need of antiemetic therapy, whichcomprises (+) norcisapride, or a pharmaceutically acceptable saltthereof, substantially free of its (−) stereoisomer.

A further aspect of the present invention includes a method of treatinga condition caused by gastrointestinal motility dysfunction in a humanwhich comprises administering to a human in need of treatment forgastrointestinal motility dysfunction, a therapeutically effectiveamount of (+) norcisapride, or a pharmaceutically acceptable saltthereof, substantially free of its (−) stereoisomer. Conditions causedby gastrointestinal motility dysfunction in a human include, but are notlimited to, gastro-esophageal reflux disease, dyspepsia, gastroparesis,constipation, post-operative ileus, and intestinal pseudo-obstruction.

Furthermore, the present invention includes a pharmaceutical compositionfor treating a condition caused by gastrointestinal motility dysfunctionin a human, which comprises (+) norcisapride, or a pharmaceuticallyacceptable salt thereof, substantially free of its (−) stereoisomer.

Further, these novel compositions may be used to treat a variety ofdisorders, as described above, while substantially reducing adverseeffects which are caused by the administration of racemic cisapride.These novel compositions may optionally contain a pharmaceuticallyacceptable carrier, excipient or combinations thereof as describedbelow.

Increased bioavailability allows for a more effective pharmacodynamicprofile than racemic cisapride or racemic norcisapride and a moreeffective management of the disease being treated. For example, a moreeffective management of disorders may be achieved with theadministration of (+) norcisapride, since dosing frequency can bereduced. This would facilitate, e.g., overnight treatment while thepatient is asleep. Similarly, a lower dose frequency may be beneficialwhen (+) norcisapride is used prophylactically or as a treatment foremesis in cancer patients.

The invention also encompasses the reduction of the cardiovascular sideeffects which is potentiated by the co-administration of cisapride withanother therapeutic agent. There can be an interaction between racemiccisapride and other therapeutic agents. For example, therapeutics whichinterfere with the metabolism of racemic cisapride, causing cisapride tobuild up in the body. This build up can cause or enhance the adversecardiovascular effects known to be associated with racemic cisapridesuch as cardiotoxicity. Thus, the presence of such therapeutics eitherfrom co-administration or sequential administration before or afterracemic cisapride can cause or enhance the adverse effects of racemiccisapride. The use of (+) norcisapride has unexpectedly been found toreduce these adverse side effects. It is believed that (+) norcisaprideboth reduces the adverse drug interactions which occur with racemicnorcisapride thereby indirectly reducing adverse effects as well asreducing the adverse effects of racemic cisapride itself. Thus, (+)norcisapride can be co-administered with drugs such as ketoconazole, anagent known to inhibit the cytochrome P450 system which is responsiblefor the metabolism of cisapride, without causing or increasing theadverse cardiovascular side effects of racemic cisapride.

Thus, the present invention encompasses methods for treating the abovedescribed disorders in a human, which comprises administering to a human(a) a therapeutically effective amount of (+) norcisapride or apharmaceutically acceptable salt thereof, substantially free of its (−)stereoisomer; and (b) another therapeutic agent. The inhibitoryco-administration problems associated with the administration ofcisapride and another therapeutic agent can be overcome by administeringoptically pure (+) norcisapride in conjunction with the therapeuticagent. Therefore, a physician need not be concerned about thecardiotoxic side effects of racemic cisapride when administering (+)norcisapride with another drug.

Other therapeutic agents to be used in conjunction with or which may beadministered during treatment with (+) norcisapride include, but are notlimited to antifungal, antiviral, antibacterial, antitumor orantihistamine agents or selective serotonin uptake inhibitors. Examplesof antifungal agents include, but are not limited to ketoconazole,itraconazole and amphotericin B. Examples of antibacterial agentsinclude, but are not limited to temafloxicin, lomefloxicin, cefadroxiland erythromycin. Examples of antiviral agents include, but are notlimited to ribavirin, rifampicin, AZT, DDI, acyclovir and ganciclovir.Examples of antitumor agents include, but are not limited to doxorubicinand cisplatin. Other agents which may be co- administered with (+)norcisapride include, but are not limited to digoxin, diazepam, ethanol,acenocoumarol, fluoxetine, ranitidine, paracetamol, terfenadine,astemizole, propranolol and other agents known to inhibit the cytochromeP450 system.

Utilizing the substantially optically pure or optically pure isomer of(+) norcisapride results in clearer dose related definitions ofefficacy, diminished adverse effects, and accordingly, an improvedtherapeutic index. Such utilization also allows the treatment of varioushuman disease states with both optically pure (+) norcisapride andanother therapeutic agent.

The term “adverse effects” includes, but is not limited to,gastrointestinal disorders such as diarrhea, abdominal cramping, andabdominal grumbling; tiredness; headache; cardiac depression; increasedsystolic pressure; increased heart rate; neurological and CNS effects;and adverse effects that result from the interaction of cisapride withother drugs that inhibit the metabolism of cisapride by the cytochromeP450 system including but not limited to ketoconazole, digoxin,diazepam, ethanol, acenocoumarol, cimetidine, ranitidine, paracetamol,fluoxetine, terfenadine, astemizole and propranolol.

The term “substantially free of its (−) stereoisomer” as used hereinmeans that the compositions contain at least about 90% by weight of (+)norcisapride and about 10% by weight or less of (−) norcisapride. In amore preferred embodiment the term “substantially free of the (−)stereoisomer” means that the composition contains at least about 95% byweight of (+) norcisapride, and about 5% or less of (−) norcisapride. Ina most preferred embodiment, the term “substantially free of its (−)stereoisomer” as used herein means that the composition contains about99% by weight of (+) norcisapride. These percentages are based upon thetotal amount of norcisapride in the composition. The terms“substantially optically pure (+) isomer of norcisapride” or“substantially optically pure (+) norcisapride” and “optically pure (+)isomer of norcisapride” and “optically pure (+) norcisapride” areencompassed by the above-described amounts.

The terms “eliciting an antiemetic effect” and “antiemetic therapy” asused herein mean providing relief from or preventing the symptoms ofnausea and vomiting induced spontaneously or associated with emetogeniccancer chemotherapy or irradiation therapy.

The term “treating a condition caused by gastrointestinal motilitydysfunction” as used herein means treating the symptoms and conditionsassociated with this disorder which include, but are not limited to,gastro- esophageal reflux disease, dyspepsia, gastroparesis,constipation, postoperative ileus, and intestinal pseudo-obstruction.

The term “prokinetic” as used herein means the enhancement ofperistalsis in, and thus the movement through the gastrointestinaltract.

The term “gastro-esophageal reflux disease” as used herein means acondition characterized by the backward flow of the stomach contentsinto the esophagus.

The term “dyspepsia” as used herein means a condition characterized byan impairment of the power or function of digestion that can arise as asymptom of a primary gastrointestinal dysfunction or as a complicationdue to other disorders such as appendicitis, gallbladder disturbances,or malnutrition.

The term “gastroparesis” as used herein means a paralysis of the stomachbrought about by a motor abnormality in the stomach or as a complicationof diseases such as diabetes, progressive systemic sclerosis, anorexianervosa, or myotonic dystrophy.

The term “constipation” as used herein means a condition characterizedby infrequent or difficult evacuation of feces resulting from conditionssuch as lack of intestinal muscle tone or intestinal spasticity.

The term “post-operative ileus” as used herein means an obstruction inthe intestine due to a disruption in muscle tone following surgery.

The term “intestinal pseudo-obstruction” as used herein means acondition characterized by constipation, colicky pain, and vomiting, butwithout evidence of physical obstruction.

The term “co-administration” as used herein means the administration oftwo therapeutic agents either simultaneously, concurrently orsequentially with no specific time limits, such that both agents arepresent in the body at the same time.

The racemic mixture of cisapride can be synthesized by the methoddescribed in European Patent Application No. 0,076,530 A2 published Apr.13, 1983, U.S. Pat. Nos. 4,962,115, 5,057,525 and 5,137,896 and in VanDaele et al., Drug Development Res. 8: 225-232 (1986), the disclosuresof which are incorporated herein by reference. The metabolism ofcisapride to norcisapride is described in Meuldermans, W. et al., DrugMetab. Dispos. 16(3): 410-419, 1988 and Meuldermans, W. et al., DrugMetab. Dispos. 16(3): 403-409, 1988, the disclosures of which areincorporated herein by reference. Norcisapride can be synthesized fromknown commercially available starting materials in accordance withstandard organic chemistry techniques. One skilled in the art cansynthesize cisapride or norcisapride by the teachings of EP 0,076,530 A2and U.S. Pat. No. 5,137,896 to Van Daele.

The (+) isomer of norcisapride may be obtained from its racemic mixtureby resolution of the enantiomers using conventional means such as froman optically active resolving acid. See, for example, “Enantiomers,Racemates and Resolutions,” by J. Jacques, A. Collet, and S. H. Wilen,(Wiley-Intenscience, New York, 1981); S. H. Wilen, A. Collet, and J.Jacques, Tetrahedron, 33, 2725 (1977); and “Stereochemistry of CarbonCompounds, by E. L. Eliel (McGraw-Hill, NY, 1962) and S. H. Wilen, page268, in “Tables of Resolving Agents and Optical Resolutions” (E. L.Eliel, Ed. Univ. of Notre Dame Press, Notre Dame, Ind., 1972).

The magnitude of a prophylactic or therapeutic dose of (+) norcisapridein the acute or chronic management of the diseases and/or disordersdescribed herein will vary with the severity of the condition to betreated, and the route of administration. The dose, and perhaps the dosefrequency, will also vary according to the age, body weight, andresponse of the individual patient. Suitable dosing regimens can bereadily selected by those skilled in the art with due consideration ofsuch factors. In general, the total daily dose range for (+)norcisapride, for the conditions described herein, is from about 0.5 mgto about 500 mg, in single or divided doses. Preferably, a daily doserange should be between about 1 mg to about 250 mg, in single or divideddoses, while most preferably, a daily dose range should be between about5 mg to about 100 mg, in single or divided doses. It is preferred thatthe doses are administered from 1 to 4 times a day.

In managing the patient, the therapy should be initiated at a lowerdose, perhaps about 5 mg to about 10 mg, and increased up to about 50 mgor higher depending on the patient's global response. it is furtherrecommended that children, and patients over 65 years, and those withimpaired renal or hepatic function, initially receive low doses, andthat they be titrated based on individual response(s) and bloodlevel(s). It may be necessary to use dosages outside these ranges insome cases as will be apparent to those skilled in the art. Further, itis noted that the clinician or treating physician will know how and whento interrupt, adjust, or terminate therapy in conjunction withindividual patient response.

Any suitable route of administration may be used in order to provide thepatient with an effective dosage of norcisapride. For example, oral,rectal, parenteral (subcutaneous, intramuscular, intravenous),transdermal, and like forms of administration may be employed. Dosageforms include tablets, troches, dispersions, suspensions, solutions,capsules, soft elastic gelatin capsules, patches, and the like.

The pharmaceutical compositions of the present invention comprise (+)norcisapride as the active ingredient, or a pharmaceutically acceptablesalt thereof, and may also contain a pharmaceutically acceptablecarrier, and optionally, other therapeutic ingredients.

The term “pharmaceutically acceptable salts” or “a pharmaceuticallyacceptable salt thereof” refer to salts prepared from pharmaceuticallyacceptable nontoxic acids or bases including inorganic acids and basesand organic acids and bases. Since the compound of the present inventionis basic, salts may be prepared from pharmaceutically acceptablenon-toxic acids. Suitable pharmaceutically acceptable acid additionsalts for the compound of the present invention include acetic,benzenesulfonic (besylate), benzoic, camphorsulfonic, citric,ethenesulfonic, fumaric, gluconic, glutamic, hydrobromic, hydrochloric,isethionic, lactic, maleic, malic, mandelic, methanesulfonic, mucic,nitric, pamoic, pantothenic, phosphoric, succinic, sulfuric, tartaricacid, p-toluenesulfonic, and the like. Preferred acid addition salts arethe chloride and sulfate salts. In the most preferred embodiment, (+)norcisapride is administered as the free base.

The compositions of the present invention include compositions such assuspensions, solutions and elixirs; aerosols; or carriers such asstarches, sugars, microcrystalline cellulose, diluents, granulatingagents, lubricants, binders, disintegrating agents, and the like, in thecase of oral solid preparations (such as powders, capsules, and tablets)with the oral solid preparations being preferred over the oral liquidpreparations. A preferred oral solid preparation is capsules. The mostpreferred oral solid preparation is tablets.

Pharmaceutical compositions of the present invention suitable for oraladministration may be presented as discrete pharmaceutical unit dosageforms, such as capsules, cachets, soft elastic gelatin capsules ortablets, or aerosols sprays, each containing a predetermined amount ofthe active ingredient, as a powder or granules, or as a solution or asuspension in an aqueous liquid, a non-aqueous liquid, an oil-in-wateremulsion, or a water-in-oil liquid emulsion. Such compositions may beprepared by any of the methods of pharmacy, but all methods include thestep of bringing into association the active ingredient with the carrierwhich constitutes one or more necessary ingredients. In general, thecompositions are prepared by uniformly and intimately admixing theactive ingredient with liquid carriers or finely divided solid carriersor both, and then, if necessary, shaping the product into the desiredpresentation.

For example, a tablet may be prepared by compression or molding,optionally, with one or more accessory ingredients. Compressed tabletsmay be prepared by compressing in a suitable machine the activeingredient in a free-flowing form such as powder or granules, optionallymixed with a binder, lubricant, inert diluent, surface active ordispersing agent. Molded tablets may be made by molding, in a suitablemachine, a mixture of the powdered compound moistened with an inertliquid diluent. Desirably, each unit dosage form, such as a tablet orsoft elastic gelatin capsule, contains from about 0.5 mg to about 250 mgof the active ingredient, and preferably from about 1 mg to about 100 mgof the active ingredient, and more preferably from about 5 mg to about50 mg. The tablet, cachet or capsule unit dosage forms may be formulatedto contain one of several dosages, e.g., about 5 mg, about 10 mg, orabout 25 mg of the active ingredient.

Because of their ease of administration, tablets and capsules representthe most advantageous oral dosage unit form, in which case solidpharmaceutical carriers are employed. If desired, tablets may be coatedby standard aqueous or nonaqueous techniques, and may be formulated forcontrolled release using techniques well known in the art.

The pharmaceutical compositions of the present invention may beformulated in a soft elastic gelatin capsule unit dosage form by usingconventional methods, well-known in the art (see, e.g., Ebert, Pharm.Tech., 1(5):44-50 (1977)). Soft elastic gelatin capsules have a soft,globular, gelatin shell somewhat thicker than that of hard gelatincapsules, wherein a gelatin is plasticized by the addition of glycerin,sorbitol, or a similar polyol. The hardness of the capsule shell may bechanged by varying the type of gelatin and the amounts of plasticizerand water. The soft gelatin shells may contain a preservative to preventthe growth of fungi, such as methyl- and propylparabens and sorbic acid.The active ingredient may be dissolved or suspended in a liquid vehicleor carrier, such as vegetable or mineral oils, glycols such aspolyethylene glycol and propylene glycol, triglycerides, surfactantssuch as polysorbates, or a combination thereof.

In addition to the common dosage forms set out above, the compounds ofthe present invention may also be administered by controlled releasemeans and/or delivery devices such as those described in U.S. Pat. Nos.:3,845,770; 3,916,899; 3,536,809; 3,598,123; and 4,008,719, thedisclosures of which are hereby incorporated by reference.

The invention is further defined by reference to the following examples,describing in detail the preparation of the compound and thecompositions of the present invention, as well as their utility. It willbe apparent to those skilled in the art that many modifications, both tomaterials and methods, may be practiced without departing from thepurpose and interest of this invention.

5. EXAMPLES 5.1. Example 1 Antiemetic Effects

The relative activities of optically pure and racemic cisapride andnorcisapride as antiemetic agents are determined by a pharmacologicalstudy in ferrets. Evaluation of these compounds is based on theirrelative potencies in a test to measure antiemesis.

Male ferrets (castrated, descented, 1.0-2.0 kg) were purchased fromTriple F Farms (Sayre, Pa.). They were housed four to a cage with 12 hlight cycle and fed ad libitum with Ralston Purina Cat Chow. Each ferretwas used non-fasted for assay after a minimum 24 hour acclimation timein the animal facility.

Ferret Preparation.

Each ferret was anesthetized with 5% isoflurane-O₂ mixture while placedfor 2-5 min. in an anesthesia chamber. The anesthetic gas was scavengedout with an exhaust hose under vacuum. The animals were removed andweighed. Injections of study compound or vehicle were made into thedorsal front paw vein (cephalic) using a tourniquet and 1 ml tuberculinsyringe with a 25 G needle while the animal was maintained underanesthesia using a small nose cone delivering 5% isoflurane-O₂. Eachforepaw was shaved for ease of vein location. Recovery time foranesthesia was 5-8 min.

Drug Preparation.

Morphine sulfate (15 mg/kg) was obtained commercially and diluted to 1mg/ml in normal saline prior to each assay. Cisplatin bulk powder wasweighed out and dissolved in normal saline heated to 75 C to make a 5mg/ml solution (90 mg placed in scintillation vial and qs with 18 mlsaline). Solution was stirred with stirring bar and kept in incubator at40 C until injected. Solution was clear pale yellow in color. Studycompound, if water soluble, was dissolved in normal saline at roomtemperature (10 mg base/10 ml) to make a 1 mg/ml solution as the base.For doses of 3.0 and 10.0 mg/kg, a solution of 5 mg/ml was prepared. Fordose of 0.001 mg/kg a solution of 0.01 mg/ml was prepared.

Assay.

Morphine emetic model: An experiment consisted of the dosing of fiveferrets for each dose of study compound and one ferret as vehiclecontrol (i.e., saline). Study compound or saline (0.5 ml) was injectedi.v. at time zero. Five minutes later, morphine sulfate 0.3 mg/kg s.c.was administered in the nape of the neck. Observations were recordedover a 30 min period after morphine injection. Cisplatin model:Cisplatin 10 mg/kg was injected i.v. in each anesthetized ferret at timezero. Normal saline (0.5 ml) or study compound was injected 30 min.later in groups of six ferrets (C=1; test=5). Observations were recordedover a four hour period.

The starting dose of study compound in both assays was 1.0 mg/kg. Dosingwas increased or decreased by one-half log increments. An attempt wasmade to test at least three doses such that percent reduction inmorphine-induced emesis or cisplatin-induced emesis was 70% or greaterwith one dose, approximately 50% with one dose, and less than 50% withone dose. These three doses and effects were used to generate an ED 50value.

Experimental Observations and Data Collection.

A cage rack holding six ferret cages was modified with plexiglass doorsand elevated cage bottoms for ease of viewing, and ferrets were placedindividually in cages. Numbers of emetic episodes and retches, and timesat which they occurred were recorded over a thirty minute time periodstarting at the time of study drug injection (morphine model). Numbersof emetic episodes and retches, and times at which they occurred wererecorded over a 4 hour time period starting at the time of cisplatininjection (cisplatin model). Emetic episode was defined as an expulsionof solids or liquid, or retching resulting in mouth opening with noexpulsion of stomach contents. Retches were defined as a rhythmicmovement of the muscles of the rib cage. Total emetic episodes andretches were averaged for each group of five ferrets and the effect oftreatment calculated as percent reduction of emetic episodes compared tocontrol values according to the formula:$\frac{{\# {episodes}\quad ({saline})} - {\# {episodes}\quad ({drug})}}{\# {episodes}\quad ({saline})} \times 100$

The mean % protection data points were used to generate an ED 50 valueusing probit analysis and RS-1 statistical package.

5.2. Example 2 Bioavailability

A single dose of test substance or vehicle is administered to malebeagle dogs either intravenously as a bolus over one minute using a 23ga butterfly needle into the saphenous vein, or as a single dose viaoral gavage. 2.0 ml of whole blood is collected from each dog prior toand at intervals of 0.083, 0.25, 0.5, 1, 2, 3, 4, 6, 9, 12, and 24 hoursfollowing the intravenous or oral administration of the optical isomersor racemic mixture of cisapride or of norcisapride. The dogs are placedin sling-restraint prior to administration of test substance and aretransferred to metabolic cages following collection of the 0.083 hourblood sample. All blood samples are collected from an angiocatheterplaced in a cephalic vein on the morning of the experiment.

The blood is drawn into a 3 cc syringe. The first 1.0-2.0 ml of blood isdiscarded. The next 2.0 ml of whole blood is quickly transferred to aheparinized tube. The heparinized tubes are kept on ice until the bloodis added. After adding the blood to the tube, the contents of the tubeare mixed and centrifuged to obtain plasma. The plasma is carefullydecanted and transferred to a test tube labelled with: the animalnumber, the dose of test substance administered, the route ofadministration, the date of administration, and the time of bloodcollection. The tubes are stored at −20° C. until analysis.

Analysis of the concentration of the optical isomers or racemates ofnorcisapride in each plasma sample is determined using high performanceliquid chromatography. For each test substance the plasma concentrationvs. sample time is plotted for both routes of administration. The oralbioavailability of each test substance is determined by comparing theC_(max) and AUC for the oral route of administration versus those forthe i.v. route. The t_(½) for each test substance by both routes iscalculated as an indicator of duration of action.

5.3. Example 3 5HT1A Receptor Activity

Receptor selection and amplification technology (R-SAT) was used(Receptor Technologies Inc., Winooski, Vt.) to determine potentialagonist and/or antagonist activity of racemic norcisapride, cisaprideand their enantiomers on cloned human serotonin 5-HT_(1A) receptorsubtypes expressed in NIH 3T3 cells (Burstein et al., J. Biol Chem.,270:3141-3146 (1995); and Messier et al., Pharmacol. Toxicol.,76(5):308-311 (1995)).

The assay involved co-expression of a marker enzyme, β-galactosidase,with the serotonin receptor of interest. Ligands stimulate proliferationof cells that express the receptor and, therefore, the marker.Ligand-induced effects can be determined by assay of the marker.

NIH 3T3 cells were incubated, plated, and then transfected using human5-HT_(1A), serotonin receptors, pSV-β-galactosidase, and salmon spermDNA. The medium was changed one day later, and after 2 days, aliquots ofthe trypsinized cells were placed in wells of a 96 well plate. Afterfive days in culture in the presence of the ligands, the levels ofβ-galactosidase were measured. The cells were then rinsed and incubatedwith the substrate, o-nitrophenyl β-D- galactopyranoside. After 16hours, the plates were read at 405 nm on a plate-reader. Each compoundwas tested for activity in triplicate at seven different concentrations(10, 2.5, 0.625, 0.156, 0.039, 0.0098, and 0.0024 nM).

None of the compounds tested showed agonist activity at human 5-HT_(1A)serotonin receptors. Data from antagonist inhibition of the compoundswere fit to the equation:${Response} = {{{Max}\quad {Response}} + \frac{\left( {{Min}\quad {Response}} \right)}{1 + \left( {{Ligand}\quad {{Conc}/{EC}_{50}}} \right)}}$

IC₅₀ values (concentration required to inhibit 50% of specific binding)were calculated for antagonist activity against a concentration of 2 μM5-HT using the non-linear least squares analysis of KaleidaGraph, theresults of which are set forth in Tables 1 and 2.

5HT2 Receptor Activity

Receptor selection and amplification technology (R-SAT) was used(Receptor Technologies Inc., Winooski, Vt.) to determine potentialagonist and/or antagonist activity of racemic norcisapride, cisaprideand their enantiomers on cloned human serotonin 5-HT₂ receptor subtypesexpressed in NIH 3T3 cells (Burstein et al., J. Biol Chem.,270:3141-3146 (1995); and Messier et al., Pharmacol. Toxicol.,76(5):308-311 (1995)).

The assay involved co-expression of a marker enzyme, β-galactosidase,with the serotonin receptor of interest. Ligands stimulate proliferationof cells that express the receptor and, therefore, the marker.Ligand-induced effects can be determined by assay of the marker.

NIH 3T3 cells were incubated, plated, and then transfected using human5-HT₂ serotonin receptors, pSV-β-galactosidase, and salmon sperm DNA.The medium was changed one day later, and after 2 days, aliquots of thetrypsinized cells were placed in wells of a 96 well plate. After fivedays in culture in the presence of the ligands, the levels ofβ-galactosidase were measured. The cells were then rinsed and incubatedwith the substrate, o-nitrophenyl β-D-galactopyranoside. After 16 hours,the plates were read at 405 nm on a plate-reader. Each compound wastested for activity in triplicate at seven different concentrations (10,2.5, 0.625, 0.156, 0.039, 0.0098, and 0.0024 nM).

None of the compounds tested showed agonist activity at human 5-HT₂serotonin receptors. Data from antagonist inhibition of the compoundswere fit to the equation:${Response} = {{{Max}\quad {Response}} + \frac{\left( {{Min}\quad {Response}} \right)}{1 + \left( {{Ligand}\quad {{Conc}/{EC}_{50}}} \right)}}$

IC₅₀ values were calculated for antagonist activity against aconcentration of 2 μM 5-HT using the non-linear least squares analysisof KaleidaGraph, the results of which are set forth in Tables 1 and 2.

TABLE 1 Calculated IC₅₀ Values (μM) at 5-HT_(1A) and 5-HT₂ ReceptorsCompound 5-HT_(1A) 5-HT₂ (±) Norcisapride 7.48 2.21 (+) Norcisapride0.0054 0.38 (−) Norcisapride 1.30 —

TABLE 2 Calculated IC₅₀ Values (μM) at 5-HT_(1A) and 5-HT₂ ReceptorsCompound 5-HT_(1A) 5-HT₂ (±) Cisapride — 0.26 (+) Cisapride — 0.0050 (−)Cisapride — 7.08

5.4. Example 4 5HT3 Receptor Binding

Racemic norcisapride, racemic cisapride and their (+)- and(−)-enantiomers were tested (Cerep, Celle l'Evescault, France) forbinding to 5HT₃ receptor subtypes derived from N1E-115 cells.

Following incubation with the appropriate ligands, the preparations wererapidly filtered under vacuum through GF/B glass fiber filters andwashed with ice-cold buffer using a Brandel or Packard cell harvester.Bound radioactivity was determined with a liquid scintillation counter(LS 6000, Beckman) using a liquid scintillation cocktail (Formula 989).

Specific radioligand binding to the receptor was defined as thedifference between total binding and nonspecific binding determined inthe presence of an excess of unlabelled ligand. Results were expressedas a percent inhibition of specific binding obtained in the presence ofthe compounds. IC₅₀ were determined using concentrations ranging from3×10⁻¹⁰ to 10⁻⁵ M to obtain full competition curves and were calculatedby non-linear regression analysis. The results are shown in Tables 3 and4 below.

5HT4 Receptor

Racemic norcisapride, racemic cisapride and their (+)- and(−)-enantiomers were tested (Cerep, Celle l'Evescault, France) forbinding to 5HT₄ receptor subtypes derived from guinea-pig striata.

Following incubation with the appropriate ligands, the preparations wererapidly filtered under vacuum through GF/B glass fiber filters andwashed with ice-cold buffer using a Brandel or Packard cell harvester.Bound radioactivity was determined with a liquid scintillation counter(LS 6000, Beckman) using a liquid scintillation cocktail (Formula 989).

Specific radioligand binding to the receptor was defined as thedifference between total binding and nonspecific binding determined inthe presence of an excess of unlabelled ligand. Results were expressedas a percent inhibition of specific binding obtained in the presence ofthe compounds. IC₅₀ were determined using concentrations ranging from3×10⁻¹⁰ to 10⁻⁵ M to obtain full competition curves and were calculatedby non-linear regression analysis. The results are shown in Tables 3 and4 below.

TABLE 3 IC₅₀ (nM) Values for Binding to 5-HT₃ and 5-HT₄ Sites Compound5HT₃ 5HT₄ 5HT₃/5HT₄ Ratio rac-Norcisapride 8.2 686 0.012 (+)Norcisapride 4.5 331 0.014 (−) Norcisapride 30.4 1350  0.023

TABLE 4 IC₅₀ (nM) Values for Binding to 5-HT₃ and 5-HT₄ Sites Compound5HT₃ 5HT₄ 5HT₃/5HT₄ Ratio rac-Cisapride 365 169 2.2 (+) Cisapride 310340 0.9 (−) Cisapride 2790  199 14.0

Agonist activity at 5HT4 receptor sites may also be assessed using anassay based on the ability of active compounds to increase cyclic AMPproduction in mouse embryo colloculi neurones grown in tissue culture(See: Dumuis et al., N. S. Arch. Pharmacol. 340: 403-410, 1989).

5.5. Example 5 Determination of Cardiovascular Effects

Unanesthetized normotensive or spontaneously hypertensive rats (SHR) areused. Blood pressure is recorded indirectly in a temperature-controlledenvironment before, and 1, 2, and 4 hours after, the test substance isadministered by an appropriate route. The test substances are racemic,(+) and (−) cisapride and racemic, (+) and (−) norcisapride. Changes insystolic blood pressure by more than 10% (>10) at any two of theaforementioned three consecutive time points is considered significant.Tachycardia is also studied. In the same normotensive or spontaneouslyhypertensive rats, heart rate is recorded by a cardiograph immediatelyafter the blood pressure recordings. An increase in heart rate greaterthan 20 percent (>20) from pretreatment control readings is consideredsignificant.

Similar studies can be performed using guinea pigs or piglets.

5.6. Example 6 Central Nervous System Effects

The effects of racemic and optically pure enantiomers of norcisaprideand cisapride on memory can be tested using the method described byForster et al., Drug Development Research, 11:97-106 (1987). In thistechnique, pharmacologic effects of drugs on memory in mice are testedusing a “discriminated escape” paradigm. Groups of mice are designatedfor vehicle and drug treatment, and each mouse is trained to enter thecorrect goal arm of a T-maze to escape an 0.8 mA foot shock deliveredthrough the floor of the apparatus. The mice are dosed with vehicle ortest compound during the training period.

The mice are initially given a preference trial in which entry to eithergoal arm will result in termination of foot shock, but they are trainedto escape the shock via the arm opposite their preference in allsubsequent trials. Mice are trained (“minimal training”) until alearning criterion of two consecutive correct choices is met.

One week after training, all mice are tested for retention of thediscrimination. The measure of retention is the percentage of correctchoice trials, i.e., those in which the mouse enters the arm of the mazein which he does not receive a foot shock. Retention of discriminationis compared for the groups of mice that have been dosed, respectively,with (+) norcisapride, (−) norcisapride, racemic norcisapride, (+)cisapride, (−) cisapride, racemic cisapride and vehicle.

Effects of racemic and optically pure enantiomers of norcisapride orcisapride on sleep can be tested using electroencephalographic analysis.Groups of rats or dogs are prepared for electroencephalographicrecordings by implanting cranial electrodes under general anesthesia,and then connecting these electrodes to an electroencephalic recordingdevice after the effects of the anesthesia have worn off. Theserecordings are made continuously, and are used to classify the sleepstate of the animal. Sleep states are classified as either “awake,”“slow-wave sleep,” or “REM sleep.” The percentage of each of the sleepstates following administration of placebo, norcisapride isomers orracemate, or cisapride isomers or racemate, is compared to evaluate thesleep-regulating effect of the tested drug.

Blockade of the conditioned avoidance response (CAR) can be used todemonstrate the ability of racemic and optically pure norcisapride orcisapride to treat the symptoms of schizophrenia. This testing procedureemploys rats that are trained to avoid a foot shock by pressing a leverat the start of a test period. The start of the test period is signaledby a non-noxious stimulus (light or buzzer). Animals that are fullytrained in this procedure will avoid the foot shock more than 90% of thetime. Compounds that are effective antipsychotics will block thisconditioned avoidance response. Thus, (−), (+), and racemic norcisaprideand cisapride are tested by administering fixed doses of test andreference compounds to trained rats and then determining their relativeeffects on conditioned avoidance.

Racemic and optically pure cisapride and norcisapride are tested forantidepressant activity using the mouse tail suspension test (Steru etal., Psychopharmacology 85:367-370, 1985). A fixed dose of (−), (+) orracemic norcisapride, or (−), (+) or racemic cisapride or a referencedrug is administered to a mouse, and the mouse is suspended about 15 cmabove the table from a hook that is taped to the tail. The animal'smovements are recorded on a polygraph. Mice typically struggle for a fewminutes, and then bouts of movement are interspersed with periods ofimmobility (“behavioral despair”). A decrease in the total duration ofimmobility during a standard test session signifies potentialantidepressant activity of the test compound.

Racemic and optically pure norcisapride and cisapride are tested foreffects on psychoactive substance use disorders by administering test orreference compound to laboratory animals, e.g., rats, that are trainedto press a lever in anticipation of receiving one of a variety ofpsychoactive substances (“drug self-administration”). Separate animalsthat have been trained to self-administer cocaine, alcohol, and morphineare employed in this study. Fixed ratios and progressive ratios are usedin setting the amount of lever pressing that is required for the animalto receive the substance. (−), (+), and racemic norcisapride orcisapride are administered at fixed doses before the standardself-administration session. A decrease in the number ofself-administrations or a reduction in the lever press/reward ratioindicates that the test compound has utility in treating psychoactivesubstance use disorders.

5.7. Example 7 Oral Formulation

Tablets Quantity per Tablet in mg. Formula A B C Active Ingredient 5.010.0 25.0 (+) norcisapride Lactose BP 62.0 57.0 42.0 Starch BP 20.0 20.020.0 Microcrystalline 10.0 10.0 10.0 Cellulose Hydrogenated Vegetable1.5 1.5 1.5 Oil Polyvinylpyrrolidinone 1.5 1.5 1.5 Compression Weight100.0 100.0 100.0

The active ingredient, (+) norcisapride, is sieved through a suitablesieve and blended with the lactose until a uniform blend is formed.Suitable volumes of water are added and the powders are granulated.After drying, the granules are then screened and blended with theremaining excipients. The resulting granules are then compressed intotablets of desired shape. Tablets of other strengths may be prepared byaltering the ratio of active ingredient to the excipient(s) or thecompression weight.

It may be apparent to those skilled in the art that modifications andvariations of the present invention are possible in light of the abovedisclosure. It is understood that such modifications are within thespirit and scope of the invention, which is limited and defined only bythe appended claims.

What is claimed is:
 1. A pharmaceutical composition which comprises (a)a therapeutically effective amount of (+) norcisapride, or apharmaceutically acceptable salt thereof, substantially free of its (−)stereoisomer; and (b) another therapeutic agent selected from the groupconsisting of an antifungal agent, an antiviral agent, an antibacterialagent, an antitumor agent, an antihistaminic agent, and a selectiveserotonin uptake inhibitor.
 2. The pharmaceutical composition of claim 1wherein the antifungal agent is ketoconzole, itraconazole, oramphotericin B.
 3. The pharmaceutical composition of claim 1 wherein theantibacterial agent is temafloxicin, lomefloxicin, cefadroxil, orerythromycin.
 4. The pharmaceutical composition of claim 1 wherein theantiviral agent is ribavirin, rifampicin, AZT, DDI, acyclovir, organciclovir.
 5. The pharmaceutical composition of claim 1 wherein theantitumor agent is doxorubicin, or cisplatin.
 6. A pharmaceuticalcomposition which comprises (a) a therapeutically effective amount of(+) norcisapride, or a pharmaceutically acceptable salt thereof,substantially free of its (−) stereoisomer; and (b) another therapeuticagent, wherein the therapeutic agent is digoxin, diazepam, ethanol,acenocoumarol, fluoxetine, ranitidine, paracetamol, terfenadine,astemizole, propranolol, or an agent known to inhibit the cytochromeP450 system.